Embodiments of the present disclosure generally relate to systems and methods for establishing a communication link between devices, and more particularly to managing dynamic connection intervals for BLE utilized to establish communication links between implantable medical devices and external instruments.
An implantable medical device (IMD) is a medical device to be implantable within a patient anatomy. Some IMDs employ one or more leads with electrodes that either receive or deliver voltage, current or other electromagnetic pulses from or to an organ or tissue for diagnostic or therapeutic purposes. Other IMDs operate without separate leads, and may be referred to as leadless IMDs. In general, IMDs include a battery, electronic circuitry, a pulse generator, a transceiver and/or a microprocessor that is configured to handle communication with an external instrument as well as control patient therapy. The components of the IMD are hermetically sealed within a metal housing.
IMDs are programmed by, and exchange data with, external instruments (EI) controlled by physicians and/or the patient. The external instruments use commercial operating systems (e.g., iOS, Android) that communicate through wireless bi-directional communication links with the IMDs. The bi-direction communication link is formed based on advertisement notices received by the external instruments. The advertisement notices are broadcast by the IMD at a predetermined constant frequency based on the wireless protocol. However, the current drain expended by the IMD to broadcast the advertisement notices can be too high where battery life is a concern, particularly in smaller devices that have limited space for batteries. To conserve current drain, it has been proposed to transmit advertisement notices at a lower frequency than defined by the wireless protocol, such as by waiting several seconds or minutes between transmission of successive advertisement notices (e.g., instead of a few seconds or milliseconds).
However, many external instruments have built in constraints related to how long the external instrument will monitor for advertisement notices for usability and power consumption purposes. If an advertisement notice is not received by the external instrument within a predetermined number of monitoring periods, the external instrument may decrease the frequency of the monitoring period. If the external instrument misses an advertisement notice, minutes may pass before the external instrument begins to monitor for an advertisement notice. When multiple unsuccessful monitoring periods occur, the battery of the external instrument is undesirably drained.
Further, many external instruments (EIs) use Bluetooth Low Energy (BLE) to connect to an IMD. The power consumption of the battery of an IMD is a major design constraint. There is a limited total amount of drain allowable for active device communications with EIs when the BLE link is active. While in an active connection, the BLE specification defines the connection interval to be the interval between two consecutive connection events (a data exchange before going back to an idle state to save power), and this connection interval can be set to a value between 7.5 ms and 4 s.
If the BLE link utilizes a protocol with connection interval 1, such as a 20 ms per packet exchange, a good data throughput is likely due to more data being exchanged during a fixed time period. However, the power consumption during the connection interval 1 will be higher during the session in which the EI is connected. Conversely, if the BLE link utilizes connection interval 2, such as a 100 ms per packet exchange, a limited data throughput bandwidth is likely due to limited data being exchanged during a fixed time period. However, the decreased power consumption during the connection interval 2 is desired and is beneficial for the longevity of the IMD. In accordance with the foregoing, conventional BLE telemetry protocols cause an undue drain on the IMD battery. A need exists for improved methods and systems to manage the connection interval of a BLE link between an EI and an IMD.